New Frontiers - New Dangers

July 20, 1969. "Houston, Tranquility Base here. The Eagle has landed." Television and radio waves carried Commander Neil Armstrong's historic exclamation to people around the world. Apollo 11’s moon landing launched a new era in human exploration and renewed the rush to gather vital scientific information about the dangers of living and working in space.

Three years and several missions later, NASA was preparing to launch Apollo 17. On August 2, 1972, five months before the scheduled mission launch, the sun erupted. A burst of radioactive particles hurtled towards the earth and moon. An estimated 100,000,000 kilograms (100 billion kg) of atomic particles, a mass equivalent to all the water in Lake Ontario, sped towards the moon at very high speeds. Solar weather forecasters called the August, 1972, solar flare a solar proton event, an extremely large coronal mass ejection that spewed vast amounts of high-energy protons into space with a force hundreds of times greater than the most violent volcanic eruptions. The radioactive particles traveled the 93 million miles (150 million km) from the sun to the moon in hours.

The first wave from this solar event bathed the earth and moon in X-rays. During a solar proton event, an intense dose of X-rays and microwaves forecasts the arrival of energized solar protons. An astronaut standing on the sun side of the moon would have been engulfed in this deadly storm of electromagnetic radiation and radioactive particles. Some experts believe the astronauts would have received a dose of more than 5,000 rems of radiation, five times the lethal dose for most people. This amount of radiation would have killed the astronauts inside their space ship as well. Fortunately for NASA the storms of this period of solar maximum subsided by December and the astronauts of Apollo 17 conducted their mission in safety.

Today, scientists are constantly gathering data from the sun and trying to learn how to predict major solar weather events. Accurate solar weather predictions are needed to help the astronauts aboard the space station prepare for dangerous bursts of solar radiation.